Recently, with the popularization of the digital living environment and the rise and development of platforms, such as internet, mobile network, radio and television network, smart television, the total demand, management, and transmission of many kinds of information have increased explosively. Therefore, the server required for storage, processing, and other functions has also increased to support the ever increasing demand.
For example, a conventional server may comprise a chassis, a storage module, a connection module, and a mainboard. The chassis comprises a base chassis. The storage module is disposed on the base chassis and provided with a storage unit. The connection module is disposed on the base chassis and connected with the storage module. The mainboard is connected with the connection module in a pluggable manner. Please refer to FIG. 1, which depicts a schematic diagram of a mainboard of a conventional server. The mainboard 100 is disposed on a base plate 101, and the mainboard 100 is provided with at least one central processing unit (not shown on Fig.), a connector (not shown on Fig.), and at least one electrical module 110. The mainboard is coupled to the connection module via the connector for transmitting signals. The electrical module may be a storage device, such as a solid state hard disk or a general hard disk. In a configuration of the mainboard, the electrical module is provided with at least one storage device, such as two hard disks 120 which are superposed on each other, and is 2.5 inches. One of the two hard disks 120 is served as an OS disk, and the other hard disk is used for storing backup data, and they are mutually redundant. The two hard disks 120 support a hot-pluggable function. Since the two hard disks 120 support the hot-pluggable function and they are mutually redundant, if one of the hard disks is malfunctioned, the other hard disk can immediately take over its work, it doesn't need to turn off the server for repairing, and doesn't affect normal function of the mainboard, so as to ensure the stability and the reliability of the server.
In above-mentioned configuration, the mainboard may be further provided with an expander card 130, such as a lower profile card which is a PCIe (Peripheral Component Interconnect Express) card having a particular specification and has advantages of occupying a smaller space and convenient assembly. Since the expander card is inserted in, the function of the server can be increased or upgraded, thereby satisfying the market requirements. However, the space of the mainboard of the above-mentioned conventional server is limited. The structure of the mainboard of the server needs to be changed if it needs to support further expander cards, controlled cards, or other electrical elements, so that the server enables to expand more functions.